The spread of Highly Pathogenic Avian Influenza (HPAI) or the avian flu in the mainland Antarctica and sub-Antarctica has raised concerns over further spread of the disease in the adjacent countries of New Zealand as well as dozens of island-nations in the Oceania.

The viral disease has claimed the lives of millions of birds worldwide.

In the wake of the spread of the disease to the Antarctica, a recent study titled Detection and spread of high pathogenicity avian influenza virus H5N1 in the Antarctic Region which is published in the journal Nature has concluded that the threat of its transmission to Australasia must be noted.

In the study, scientists warned that spread of the H5N1HPAI clade 2.3.4.4b in Falkland Islands and South Georgia holds significance as they host a rich avian biodiversity and are deemed as a protected area for the avian species.

South Georgia alone is known to be home to 29 avian species that breed on the island. The island located in the Southern Ocean inside the Antarctic convergence, is labelled as an ‘Important Bird Area’ by Birdlife International — a global partnership of non-governmental organisations that strives to conserve birds and their habitats.

Hence, the detection of infection on the island has the potential to directly impact the wider population of seabirds, the study noted.

It also observed that the island witnesses high degree of species overlap within colonies, enabling free interaction of bird species, which can possibly accelerate the spread of the disease.

The authors noted that detection of H5N1 in avian and mammal species in an interlinked ecosystem across the Antarctic region shows potential for the virus to reach across wider geographic areas of the mainland region.

“Circumpolar and trans-Pacific migrants such as grey-headed albatross, white-chinned petrel, southern giant petrels, and northern giant petrels (Macronectes halli) may facilitate this spread,” the study mentioned.

Joining the dots of viral infection

The study stated that a phylogeographic analysis has indicated that a dynamic gene flow between southern Atlantic populations and Macquarie Island (an island in the southwestern Pacific Ocean, almost halfway between New Zealand and Antarctica). This analysis establishes an increased threat to transmission to New Zealand and Australasia.

One of the remotest environments on the planet, the Antarctica is also the site that houses breeding colonies for a wide diversity of avian species that can get infected with HPAI.

What makes outbreak in the Antarctica worse is that the survivability of the virus increases with the colder environments which expands the possibility of the virus in sustaining themselves for longer durations in the carcasses that remain preserved in the local climate.

The study further found that low density nesting birds such as wandering albatross may limit the spread but non-breeding birds that congregate to display mating dance may enable spread of the disease.

Penguins which nest in high densities varying on the species may make them susceptible to the disease spread. Though limited spread has been observed so far, it may impact highly, if the disease starts spreading rapidly.

Sigh of relief

The scientists, however, stated that the above mentioned threat is less likely as the outbreak in Gentoo penguin reported earlier has not led to mortalities or dissemination within the population.

The scientists have found no further adaptation of the virus for enhanced infection in mammals apart from fur and elephant seals, putting the human population living in the region at low risk from the viral infection.

“It is of high interest to understand what impact repeat introduction events may be having in the region. Currently, there are only a limited number of sequences deposited in public databases from H5N1 HPAIV detections in South America during summer 2023, which limits interpretation,” the study observed.

But so far, the global scientific community continues to monitor the situation in Antarctica and it remains to be seen if the outbreak unfolds as an ecological disaster in the region.

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